This invention relates to a structure of connection between a reversed-type steering roll connector (hereinafter referred to as xe2x80x9cSRCxe2x80x9d) and a steering wheel.
In vehicles, there has heretofore been used a SRC by which electrical equipments, mounted on a steering wheel (which is operated or turned), are electrically connected to electrical equipments mounted on a vehicle body. In one such conventional SRC, a flat cable is received in a spirally-wound condition in an annular receiving portion formed between a fixed case (stator) and a rotating case (rotator), and one end of this flat cable is connected to a connector portion on the fixed case, while the other end thereof is connected to a connector portion on the rotating case. In this case, the rotating case rotates together with the steering wheel (see, for example, JP2001-270446A).
In recent years, there have been extensively used so-called reversed-type SRCs in which the length of a flat cable can be reduced. In such a reversed-type SRC, a ring member is received within an annular receiving portion, formed between a fixed case and a rotating case, so as to move in a direction of the circumference of this receiving portion, and a plurality of rollers are rotatably mounted on this ring member, and are spaced from one another in the circumferential direction. A flat cable is received in this receiving portion in such a manner that the direction of winding of the flat cable is reversed by one of the plurality of rollers. In this construction, also, the rotating case rotates together with a steering wheel (see, for example, JP2001-165607A).
Although the above reversed-type SRC has an advantage that the length of the flat cable can be reduced, it has the following disadvantage. Namely, an intermediate portion of the flat cable is reversed into a generally U-shape, and therefore stresses are always exerted on this reversed portion of the flat cable. When the steering wheel is operated or turned, a pushing force and a pulling force act on the flat cable via the rotating case. Particularly when the steering wheel is turned or swung right and left, a pushing force and a pulling force repeatedly act on the flat cable, and as a result there was a fear that the durability of the flat cable was lowered.
This invention has been made in view of the above circumstances, and an object of the invention is to provide a structure of connection between a reversed-type SRC and a steering wheel, in which the durability of a flat cable of the SRC is enhanced.
In the invention, the above object has been achieved by a connecting structure for a vehicle comprising:
a steering wheel connected to a distal end portion of a steering shaft;
a reversed-type steering roll connector including,
a fixed case fixed to a vehicle body of the vehicle,
a rotating case rotatable with respect to the fixed case, which cooperates with the fixed case to form an annular receiving portion a center of which corresponds to the steering shaft,
a ring member received in the receiving portion, movable in a direction of a circumference of the receiving portion,
a plurality of circumferentially-spaced rollers rotatably mounted on the ring member, and
a flat cable which is received in a spirally-wound condition in the receiving portion in such a manner that a reversed portion at which a direction of winding of the flat cable is reversed by one of the rollers is formed intermediate opposite ends of the flat cable, one of the opposite ends of the flat cable being connected to the fixed case while the other end thereof is connected to the rotating case;
an escape groove having a shape of an end-closed annulus a center of which corresponds to the steering shaft, formed in one of the rotating case and the steering wheel; and
a convex portion received in the escape groove, which is movable along the escape groove and is formed on the other of the rotating case and the steering wheel.
In the above construction, when the steering wheel is operated or turned, the convex portion, received in the escape groove, moves relative to this escape groove therealong. Within the range of movement of the convex portion in the escape groove, a rotating force of the steering wheel is not transmitted to the rotating case of the SRC, and therefore the rotating case does not rotate, and hence remains there. Then, when the convex portion abuts against an circumferential end of the escape groove, the rotating case rotates together with the steering wheel in the same direction. Therefore, even when the steering wheel is operated or turned, the rotating case will not rotate until the convex portion, received in the escape groove, abuts against the circumferential end of the escape groove, and therefore the amount of movement of the rotating case of the SRC and hence the amount of movement of the flat cable can be reduced. As a result, stresses, acting on the flat cable, can be reduced, so that the durability of the flat cable can be enhanced. And besides, since the amount of movement of the flat cable is reduced, the length of the flat cable can be further reduced.